Please read further if the errors you're getting when trying to send to Gmail users look like this, or one stating Gmail couldn't verify the email came from your domain name:
⚠️Be careful with this message...
host gmail-smtp-in.l.google.com[22.214.171.124] said:
550-5.7.1 [126.96.36.199 12] Our system has detected that this message
is 550-5.7.1 likely unsolicited mail. To reduce the amount of spam sent to
Gmail, 550-5.7.1 this message has been blocked. Please visit 550-5.7.1
https://support.google.com/mail/?p=UnsolicitedMessageError 550 5.7.1 for
In an effort to reduce spam received by their users, Gmail/Google has begun to label any email received from senders who aren't using a DNS SPF record "spam," and thereby requiring senders to add an SPF record, if they want to send to Gmail users.
You must visit your domain name host, and add a text record that looks like this, at a minimum, to meet Gmail/Google's new requirements, and to be able to once more send email to Gmail users:
v=spf1 include:_spf.zmailcloud.com ~all
As an example of how to do this, here's GoDaddy's instructions on how to add an SPF record: https://www.godaddy.com/help/add-an-spf-record-19218 Of course, you may want to look for instructions specific to your particular domain host.
Note that if you're sending through other mail systems too, such as your own website, you'll want to list them in your SPF record as well. Please reference our knowledgebase article on SPF, and if you have trouble or questions, open a ticket with us for help including whichever other mail systems you may need: https://admin.cloudiance.com/knowledgebase.php?action=displayarticle&catid=2&id=47
Background: Gmail/Google started requiring extra "authentication" for email sent to their users earlier this year. At that time, we made an earlier pubic announcement about it here, where you can find much more detail: https://admin.cloudiance.com/announcements/28/Google-requiring-authentication-to-send-email-to-Gmail-users.html
Wednesday, June 8, 2022